A number of undesirable or dangerous conditions are associated with particular sleep postures such as a supine sleep posture. One such condition is sleep apnea, i.e., interruption of respiration causing a decrease in blood oxygen levels and if unattended, causing death. Another such condition is snoring. Both such conditions are associated with supine sleep i.e., sleep lying on one's back, and are believed by many researchers to be particularly associated with deeper sleep.
Several types of apparatus have been previously suggested for treating or attending to such conditions. Some approaches, e.g., as described in U.S. Pat. No. 3,485,241, issued Dec. 23 1969, to Polley and U.S. Pat. No. 132,500, issued Oct. 22, 1872, to Sullivan, include protruding devices which act as physical barriers to turning on one s back. Other approaches including those described in U.S. Pat. No. 2,304,235, issued Dec. 8, 1942, to Boots, U.S. Pat. No. 898,379, issued Sept. 8, 1908, to Liebhardt, U.S. Pat. No. 876,491, issued Jan. 14, 1908, to Rohwer, and U.S. Pat. No. 663,825, issued Dec. 11, 1900, to Wilson, disclose ball-like or prodding devices disposed at a single position near the back of a sleeper. Experience with a variety of devices indicates that there is a tendency during sleep to place a wearable device in an ineffective position, where possible, in order to achieve supine sleep. For example, a device can be positioned under or below the level of the scapula so that the sleeper rests on his scapula instead of the device. Experience with single-prod devices indicates that effectiveness is defeated when the relatively small surface area of contact of the device becomes positioned during sleep in a relatively ineffective or insensitive area of the back of a sleeper, such as near the shoulder blade or hip.
Other approaches, such as described in U.S. Pat. No. 675,017, issued May 28, 1901, to Roush and German Patent No. 6425, issued July 25, 1879, to Kollosser, disclose devices with more than one contact device in a linear configuration. Experience with a linear configuration has also shown its susceptibility to placement in an ineffective position during sleep.
Previous devices generally approach the problem from the viewpoint that supine sleep must be prevented and show no awareness that, in addition to preventing supine sleep, undesired consequences thereof can be avoided using a device which can operate during supine sleep. In accordance with this belief, previous approaches were directed to producing complete awakening of a sleeper if the sleeper assumed a supine position and thus prevented an uninterrupted full night's sleep. Further consistent with the previous approaches, the prior devices did not provide for adjusting the degree of sharpness of the device with respect to the sleeper (i.e., the sharpness as felt by the sleeper), and thus did not include apparatus or methods for accommodating sleepers with varying weights sensitivities depth of sleep, and the like.
Accordingly, there is a need for a device with sufficient contact area to assure contact with sensitive regions of a sleeper, which does not require absolute prevention of supine sleep or full awakening of a supine sleeper, and of a method for adjusting an arousal device to suit the needs and circumstances of individual sleepers.